内压作用下的航空轮胎爆破碎片动力响应

航空轮胎爆破时受内压释放的影响,爆破碎片的速度会有明显增加,而非与适航标准规定的与轮胎降落时的胎速相同。利用Fluent中用户自定义函数编写动力响应程序,采用动网格和用户自定义函数相结合的方法,展开内压释放作用下的轮胎爆破碎片速度动力响应特性的数值模拟研究。假设轮胎爆破失效是存在先前缺陷造成的,将碎片受冲击后的动态过程分解为内压释放冲击加速阶段和以一定初速度在空气阻力下减速运动两个阶段,提出仅考虑碎片两侧实时压力差作为动力源的简化物理爆破模型,来分析碎片的速度受内压作用的响应和整个流场压力以及速度变化情况,弥补了数学模型未考虑内外压平衡过程的不足,为预测轮胎爆破后碎片获得能量和爆破气流能量等提供数值参考,以便提出相应的安全防范措施。

Dynamic response of aircraft tire bursting debris under internal pressure

When the aircraft tire bursts,the velocity of the debris will be significantly increased because of the impact of internal pressure,rather than remain consistent with that of the tire in landing as specified by airworthiness standards.The model for dynamic response of bursting debris under internal pressure releasing is simulated by using dynamic grid and user defined function in Fluent,and the dynamic response program is coded by using the user defined function.Tire bursting failure is assumed to be caused by previous defects of the tire,and the dynamic process of debris can be decomposed into two phases:acceleration phase under the impact of internal pressure releasing,and deceleration motion phase under air resistance.The real-time pressure difference between both sides of debris is regarded as the only power source of the simplified physical burst model for analysis of the velocity of debris,the flow field pressure and velocity changes affected by internal pressure.The reduction model makes up the deficiency that previous mathematical models do not take into account the balance of internal and external pressure.The model can provide numerical reference for predicting the energy of debris after bursting and the energy of bursting airflow,and can thus help with the proposal of corresponding safety precautions.